Variable control device



Oct. 30, 1928. 1,690,077

L. a. PACENT VARIABLE CONTROL DEVICE Filed June 1923 INVENTOR BY I W MATTORNEY and the like.

Patented 0a. 30, 1 928.

"U TED T TES 1,690,077 PATENT OFFICE.

Louise. racism, or WIN-FIE D, new YORK. assIGNoR 'ro rncnn'r ELECTRICoom- Jenny, INC.,0F NEW YORKLN. Y., A conroanrron or NEW YORK.

VA RIA BLE oonrnor. mivron.

. j Application filed June a, 1923. Serial 116144.299;

Thisinventionhas to'do with ,devicesfor manually controll ng ElGCtIICalapparatus and more especially-"high frequency apparatus such asvariablecondensers, variometers The invention relates, more particularly, towhat are commonly termed Vernier adjust: ment devices and, specifically,to control knobs and dials provided with instrumentali' ties for.effecting very fine rotary adjustments of the electrical. apparatus towhich it} may beattached. V

with highly a selective circuits adjustments areffreqnentlysocriticalth'at it is CllfllCll'lt to tune in desired transmittingstations with the control knobs ordinarily provided. Under thesecijrcumstanc'es it becomesdesirable to equipfthe radio receivinginstrument with devices designed for effecting micrometric adjustments.i V i o-called Vernier adjustment devices have heretofore been providedparticularly in conjunction with variablecondensers. The most common oftheseis the well-known Vernier condenser comprising two sets ofrotatable plates mounted on concentric shafts and provided withconcentric control knobs. One of the sets of rotatable plates usuallyconsists of a single plate which is operable to effect fine capacityadjustments while the other i set is operable for coarse adjustments.Other arrangements have been proposed which do not involve separatelyrotatable elements for the fine adjustments. In so far as it has beenpossible to ascertain, .none of'these contenr plates the provision of anintegral self-con tained device which is operable for effecting bothcoarse and fine adjustments. 4

The principal object of the present invention is to provide a simple andinexpensive device for effecting micrometric adjustments of ordinaryvariable electrical apparatus such as variable condensers, variometers,variocouplers and the like which can be connected In radioreceiving"instruments provided The preferred embodimentfof the inventionis. characterized by extreme simplicity and comprises two coaxial knobsone of which is" fixed to the'shaft and the other mounted thereon butfree to'rotate independently thereof. Awvheel having prefer ably arubber rim is" 'pivotally'attached to the fixed knob and disposed, inpart at least. inside thereof. This wheel, which is appro priatelyreferred to hereinafter as atraction. wheel,1sarranged'to frlctionallyengage the panel and the free knob conjointly, 'thear-L rangement beingsuch that rotation of the free knob may rotate the traction wheel which,by reason of its frictional engagement with the panel, revolves aboutthe axis ofthe shaft and carries the fixed'kn ob with it, thus rotatingthe shaft." The .drivii'ig ratio between the free knob and the fixedknob is a predetermined factor and is, in general of such value that thefree knob makes several revolutions for eachrevolution of the shaft.Thus it will be seen that very fine rotary adjustments of the shaft canbe easily effected by rotating the free knob and coarse adjustments canbe made by rotating the fixed knob. I

It is thought that a clearer understanding of the invention may be hadfrom the following detailed description in conjunction with theaccompanying drawing, in which i Fig. l isa cross sectionalview of avariable control device in accordance with the preferred embodiment ofthe invention;

Fig. 2 is a front elevation of the device; Fig. 3 is a rear elevation ofthe device; and Fig. 4 is a rear elevation of the fixed knob with thedial part thereof removed in order to show the traction wheel and itssupport more in detail.

i any variable electrical instrument suchas'a variable condenser,variometer or variocoupler, and 1s shown pro ecting through a f mountingpanel 2, on which the instrument to be controlled may be mounted. A knob33,

comprising two parts 3 and 3 is fixedly secured to the shaft by means ofa set screw 4. The parts 3 and 3 are fastened together by three flathead machine screws 5. The

part3 is graduated as shown in Fig. 2, and

forms the usual dial for indicating the setting of the instrument.

loo

A metal bushing 6 is bored to receive shaft thereto by the flat headmachine screw 12.

The free knobis-rotatable about the bushing (3 independently ofany:rotation of shaft l or knob 2h It will be noted that the screw 12.

does not clamp the free knob against the endol bushing 6 and that thefunction, oi. this screw is merely to prevent the free knob fall'- ingoil the bushing.

As is clearly shown in Fig. l, the free knob ll has a frusto-eonicalportion 11 the surface of which is adapted to engage the the 10 oftraction wheel 5). rotation of the tree knobll imparts a rotary movementto*the traction wheel causing it to revolve about the axis of sha ft 1by reason of its t actional engagement with panel 2. Since the tractionwheel is attached to knob 3, revolution of the former will cause thelatter to rotate carrying with it the shaft 1. The

driving ratio between the free knob 11' and the fixed knob 3 ispreferably such that severalrevolutions of the former are required to ettect one revolution of the latter.

According to the preferred arrangement When thus engagedas shown inFig.1, thereis normally some clearance between either the freeknob andthe traction wheel or between the traction wheel and the panel, so thatit is neceeeary to press slightly on the free kuobin order to cause thetract-ion Wheel to effectively engage both the free knob and the panel.It is notnetessary, however, to provide this clearance.

In operation the instrument is adjusted to the approximate setting bydirect rotation o'l the fixed knob 3, after which the fiiieadjustment'is obtained by turning the free knob 11, exceedingly tinerotary adjustments being thereby obtainable with no dilliculty.

It is realized that a great many modificationsand alternativearrangements are possible within the scope and'spirit of this invention,audit should not therefore be construed as limited except by the scopeof the appended claim.

I claim:

A variable control device comprising an adjustingmember engageable witha shaft, a swinging pivot pin pivotally connected with said member atone end, aroller journalcd on the free end of said pivot pin andanadjusting knob 'journaled'on eaidmemberaiul engageable with the outerrim of said roller to therebyswing the pivot pin inward to of feetengagement of the inner rim of the roller with a stationary surface atthe bucket" the adjusting member.

In testimony whereof L afllx my signature.

